A daily dose of postings from The Chronicle's technology blog (sfgate.com/blogs/tech)

The browser wars continue to heat up. On Tuesday, Apple released Safari 4, which it hails as the world's fastest and most innovative browser.

There are reportedly about 150 improvements and new features in Safari 4, which is available for both Mac OS X and Windows. First off, Apple said it's sped up the loading of HTML pages by about three times over Internet Explorer 7 and Firefox 3. Thanks to a new Nitro JavaScript engine, Safari 4 also can execute Javascript three times faster than Firefox.

Safari 4 appears to re-use some ideas seen in Google Chrome, including tabs along the top and a Top Sites page. Like Chrome, favorite pages are assembled on one screen, but Apple being Apple, its version is prettier and curved, giving you the sensation of looking at a 3-D page.

Cover Flow is also brought to bear on Safari 4's history and bookmarks page, so you can flow through pages as you do cover art in iTunes. There's also a full history search function, so you can search through titles, Web addresses and the complete text of recently viewed pages.

Larry Brilliant, the high-profile leader of Google's philanthropic arm, said Monday that he will step down and indicated that the organization might narrow its focus.

He will become Google.org's chief philanthropy evangelist, a role he said would involve identifying "big ideas" and potential partners, according to a blog post.

Megan Smith will take over from Brilliant while keeping her role as Google vice president of new business development.

The changes to Google.org mark a major shake-up for the 3-year-old organization, which has funded a number of projects involving clean energy and infectious diseases. Brilliant said that the shift follows a review of the philanthropy's progress since its founding and planning for its future, which he signaled would include investment in projects that are more closely aligned with Google's expertise and business interests.

Google.org's current projects include developing clean energy that is cheaper than coal, a Web site called Flu Trends that tracks flu outbreaks, and PowerMeter, a new service that would allow consumers to more closely monitor their energy use.

Brilliant, a doctor who gained a widespread acclaim for his work fighting smallpox and polio in the developing world, gave Google.org extra credibility when he became the organization's first leader. Unlike a charity, Google.org makes for-profit investments in businesses engaged in what is known as social entrepreneurism.

Some of Google's engineers switch back and forth between working for Google and Google.org.